One-pot tandem reactions for the preparation of esterified cellulose nanocrystals with 4-dimethylaminopyridine as a catalyst

Abstract

An efficient approach for the manufacture of esterified cellulose nanocrystals (E-CNCs) via one-pot tandem reactions with 4-dimethylaminopyridine (DMAP) as a catalyst under mild operating conditions is put forward. The effects of ball milling time, reaction temperature and ultrasonication time on the yield and degree of substitution (DS) are explored. Characterization indicates the successful esterification of the hydroxyl groups of cellulose. The micromorphology and microstructure of the prepared E-CNCs are studied using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Results show that the E-CNCs are short rod-like particles 130–230 nm in length and 20–40 nm in width, forming an interconnected network structure. X-ray diffraction (XRD) results indicate that the crystallinity index increases from 63.5% to 77.2%. The thermal properties of the E-CNCs are investigated by thermogravimetric analysis (TGA) and the results show that the E-CNCs exhibit higher thermal stability than cellulose pulp.